Integrated circuits and other circuit elements within electronic devices commonly require an input voltage that is smaller than that supplied by a regulated D.C. power source. For example, an integrated circuit within a computer system may require a powering voltage of about 2.5 volts D.C. from a standard 3.3 volt regulated D.C. source. To that end, voltage regulators have been developed that reduce an input D.C. voltage to a preselected, lower voltage.
Many such prior art regulators, such as linear converters, have a relatively low efficiency (i.e., between about fifty and sixty five percent) when used in high current applications. Accordingly, when used in high current applications, linear converters typically require relatively large heat sinks to dissipate a large amount of heat produced by the voltage reduction process. This heat loss necessarily increases the operating cost of such converters. Moreover, the requirement of a heat sink increases the size and manufacturing cost of each converter.
The art has responded to this efficiency problem by providing switching voltage converters ("buck converters") that dissipate minimal heat in high current (as well as low current) applications. Accordingly, buck converters typically operate at efficiencies of between about seventy and ninety-five percent. Buck converters typically utilize an inductor and a switch that cooperate to reduce the input voltage to a preselected output voltage. The duty cycle of the switch in buck converters, however, can be greater than about ninety percent. This causes the switch to generate excessive heat, especially when used in high current applications. Accordingly, a large switch with a relatively large heat sink often is utilized to dissipate the excess heat. This necessarily increases the cost associated with producing and operating such buck converters.